﻿using System;
using System.Globalization;
using System.Windows;
using System.Windows.Data;

namespace Foundation.Converters
{
    /// <summary>
    /// Null Converter.
    /// </summary>
    public class NullConverter : FrameworkElement, IValueConverter
    {
        /// <summary>
        /// Gets or sets the on null.
        /// </summary>
        /// <value>
        /// The on null.
        /// </value>
        public object OnNull { get; set; }

        /// <summary>
        /// Gets or sets the on not null.
        /// </summary>
        /// <value>
        /// The on not null.
        /// </value>
        public object OnNotNull { get; set; }

        /// <summary>
        /// Converts a value.
        /// </summary>
        /// <param name="value">The value produced by the binding source.</param>
        /// <param name="targetType">The type of the binding target property.</param>
        /// <param name="parameter">The converter parameter to use.</param>
        /// <param name="culture">The culture to use in the converter.</param>
        /// <returns>
        /// A converted value. If the method returns null, the valid null value is used.
        /// </returns>
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            return value == null ? OnNull : OnNotNull;
        }

        /// <summary>
        /// Converts a value.
        /// </summary>
        /// <param name="value">The value that is produced by the binding target.</param>
        /// <param name="targetType">The type to convert to.</param>
        /// <param name="parameter">The converter parameter to use.</param>
        /// <param name="culture">The culture to use in the converter.</param>
        /// <returns>
        /// A converted value. If the method returns null, the valid null value is used.
        /// </returns>
        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            return Equals(value, OnNotNull) ? new object() : null;
        }
    }
}
